Self-cleaning spray nozzle

Abstract

A spray nozzle comprises a hollow body having an inlet, an outlet and a fluid flow passage therebetween. The body contains a pressure-responsive or a pressure responsive and temperature responsive valving element that increases the effective area of the outlet in response to an increase in pressure or an increase in pressure and/or temperature. In a preferred embodiment, the outlet includes a restricted orifice and an unrestricted orifice, and the valving element is movable within the body between a first position in which the restricted orifice is open and the unrestricted orifice is closed, and a second position in which the unrestricted orifice is open. The valving element is biased in the first position by a spring which applies a selectable biasing force that defines a threshold pressure, so that the valving element is moved to the second position by a dynamic pressure of the fluid flowing through the flow passage that is greater than the threshold pressure. In an alternative embodiment, the outlet is provided with a resilient occluder having an orifice that increases in area as the occluder is flexed axially in the downstream direction in response to an increase in the dynamic pressure of the fluid flow.

What is claimed is: 
     
       1. A spray nozzle for continuously feeding a solution of soap in water under low pressure to lubricate a conveyor, comprising: a.) an elongate fitting defining a hollow passage for the flow of the solution, the fitting having inlet and outlet ends for the soap solution, the inlet end being fed by the soap solution, and the outlet end defining a valve seat and a wedge-shaped gap formed thereon, the fitting being outwardly tapered at the outlet end, and peripherally thereof to deflect a flow of soap solution, and thereby produce a spray;   b.) a poppet valve comprising a threaded valve stem and a rotatably adjustable poppet head, the valve stem being disposed centrally and axially within the hollow passage of the fitting, and the poppet head being seatable on the valve seat and adjacent the wedge-shaped gap;   c.) a coil spring surrounding the valve stem within the fitting and adapted for upward biasing against the poppet head to close the poppet head against the valve seat;   d.) a threaded retainer mounted on the valve stem for biasing the spring against the poppet head when the poppet head is adjusted, the poppet head being unseatable by pressure of the soap solution; and,   e.) a conveyor associated with a plurality of the spray nozzles, the conveyor being adapted to move food containers and packages thereon;   whereby:   i. outward or inward rotational adjustment of the poppet head through the threaded retainer will adjust compression by the spring against the poppet head onto the valve seat and against the pressure of the soap solution, to control the outlet flow from the wedge-shaped gap, thereby changing spray volume and correspondingly changing the volume of a continuous stream of the soap solution applied to the conveyor when the poppet head is unseated by the pressure of the incoming soap solution;   ii. the poppet valve can be cleaned by increasing the soap solution pressure to unseat the poppet head, or by retracting the poppet head away from the outlet of the fitting against the force of the spring bias, thereby cleaning the nozzle outlet, without interrupting the feed of soap solution to the conveyor;   iii. after the nozzle has been cleaned, the poppet valve is released to reseat on the nozzle outlet; and,   iv. the conveyor is adapted to maintain movement during periods of nozzle outlet cleaning, with reduced contamination by microorganisms.   
     
     
       2. The spray nozzle of claim 1, which includes washer means mounted against and under the poppet head, and sealing the nozzle against leakage when the poppet head is seated on the valve seat. 
     
     
       3. The spray nozzle of claim 1, defining an outer, shaped periphery for engagement by a wrench means. 
     
     
       4. The spray nozzle of claim 1, in which the threaded retainer at its outer periphery forms a loose sliding fit with the hollow passage of the fitting, thereby maintaining the valve stem aligned centrally and axially within the hollow passage of the fitting. 
     
     
       5. The spray nozzle of claim 1, in which the poppet head is shaped for engagement with a tool to retract the poppet head away from the outlet of the fitting, thereby enabling the fitting to be cleaned. 
     
     
       6. The spray nozzle of claim 1, in which the spring biasing is adjustable to line pressures of from 10 psi to 70 psi. 
     
     
       7. The spray nozzle of claim 1, in which the spring biasing is adjustable to line pressures of 10 psi at 0.014 gallons per minute to 40 psi at 0.048 gallons per minute. 
     
     
       8. A method for continuously feeding through a spray nozzle a solution of soap solution in water under low pressure to lubricate a conveyor, the spray nozzle comprising: a.) an elongate fitting defining a hollow passage for the flow of the solution, the fitting having inlet and outlet ends for the soap solution, the inlet end being fed by the soap solution, and the outlet end defining a valve seat and a wedge-shaped gap formed thereon, the fitting being outwardly tapered at the outlet end, and peripherally thereof to deflect a flow of soap solution, and thereby produce a spray;   b.) a poppet valve comprising a threaded valve stem and a rotatably adjustable poppet head, the valve stem being disposed centrally and axially within the hollow passage of fitting, and the poppet head being seatable on the valve seat and adjacent the wedge shaped gap;   c.) a coil spring surrounding the valve stem within the fitting and adapted for upward biasing against the poppet head to close the poppet head against the valve seat;   d.) a threaded retainer mounted on the valve seat for biasing the spring against the poppet head when the poppet head is adjusted, the poppet head being unseatable by pressure of the soap solution; and,   e.) a conveyor associated with the spray nozzle, the conveyor being adapted to move food containers an packages thereon; the process comprising:   i. outwardly or inwardly rotationally adjusting the poppet head through the threaded retainer to adjust compression by the spring against the poppet head onto the valve seat and against the pressure of the soap solution, to control the outlet flow from the wedge-shaped gap, thereby changing spray volume and correspondingly changing the volume of a continuous stream of the soap solution applied to the conveyor when the poppet head is unseated by the pressure of the incoming soap solution;   ii. cleaning the poppet valve by increasing the soap solution pressure to unseat the poppet head, or by retracting the poppet head away from the outlet of the fitting against the force of the spring bias, thereby cleaning the nozzle outlet, without interrupting the feed of soap solution to the conveyor;   iii. after the nozzle has been cleaned, releasing the poppet valve to reseat on the nozzle outlet; and,   iv. the conveyor being adapted to maintain movement during periods of nozzle outlet cleaning, with reduced contamination by microorganisms.   
     
     
       9. The method of claim 8, in which the spring biasing is adjustable to line pressures of from about 10 psi-70 psi. 
     
     
       10. The method of claim 8, in which the spring biasing is adjustable to line pressures of from about 10 psi at 0.014 gallons per minute to about 40 psi at 0.048 gallons per minute.